Search

Neonatal pertussis can potentially cause severe complications and even death. Mothers have been most frequently identified as the source of neonatal pertussis. Approximately a dozen countries have implemented pertussis vaccination programs for pregnant women to protect neonates; however, in Japan, this has not been implemented. The aim of this questionnaire-based study was to ascertain the willingness of women to be vaccinated during pregnancy and the factors associated with willingness. The subjects were 977 pregnant women who visited either of the two selected hospitals for maternity health checks. Most of the women were in their first pregnancy (96%), and approximately half of them considered a physician to be the most reliable source of information about vaccination (481/977, 49%). "Willingness to receive pertussis vaccination" was significantly associated with the factors "no fear of receiving vaccination" (odds ratio [OR] = 3.10, 95% confidence interval [CI]: 2.21-4.34), "necessary to prevent pertussis" (OR = 8.70, 95% CI: 6.17-12.28), "effective in pregnancy" (OR = 5.46, 95% CI: 3.94-7.56), and "no concern about the side effects after vaccination" (OR = 3.03, 95% CI: 1.66-5.55). Pregnant women are likely to consider vaccination if they have a good understanding of the disease and its outcomes. Physicians are well positioned to improve knowledge and attitudes toward pertussis vaccination during pregnancy.

Background Hypotonic-hyporesponsive episode (HHE) after whole cell pertussis vaccination is a known adverse event. Less is known about the risk of HHE after administration of acellular pertussis vaccines. Methods Using parental interviews, this study actively surveyed for HHE among infants after doses 1 and 2 of acellular pertussis vaccine. Results We interviewed the parents of 52,531 infants. HHE was reported at a rate of 22.8 per 100,000 doses (95% CI: 11.8-39.9) of acellular pertussis vaccine, approximately 45 episodes per 100,000 children. Conclusions These rates are lower than HHE rates reported after whole cell pertussis vaccines and within the range of HHE rates reported in other studies of acellular pertussis vaccines.

This cross-sectional study assessed prenatal pertussis vaccination acceptance in Taiwan. A sample of pregnant women from five private clinics in Taiwan was recruited. Demographics, experience of prenatal vaccinations, key considerations, knowledge, and attitude about pertussis and its vaccination were measured. Among 505 participants, the vaccination rate, including planned vaccination, was 29.7%. Factors associated with acceptance included clinic location, primary caregiver of the newborn, newborns with siblings, previous influenza vaccination history, knowledge and attitude toward pertussis and its vaccination. Public health agencies should provide free vaccinations, clarify misinformation, and publicize prevention information, to improve prenatal pertussis vaccination acceptance.

Objective: to investigate pertussis vaccination rates during pregnancy and the routine recommendation rates by maternity healthcare professionals (HCPs), including influencing factors, in Korea. Materials and methods: Two different questionnaires were developed and conducted anonymously for pregnant or postpartum women and maternity HCPs in 30 multi-centers. Maternal pertussis vaccination rates and maternity HCPs’ recommendation rates were analyzed. Independent influencing factors were analyzed using multivariate logistic regression analysis, respectively. Results: The rate of pertussis vaccination during pregnancy among 466 women was 67%. Among 164 multiparous women, 35.5% received pertussis vaccinations during every pregnancy. However, 27.9% among all pregnant women did not receive information about pertussis and vaccination. The independent influencing factors for maternal pertussis vaccination, given as the tetanus, diphtheria and acellular pertussis (Tdap), were “getting informed” (OR 18.597, 95% CI 11.206–30.861), “informed by OBGYN doctors” (OR 4.426, 95% CI 2.144–9.267), and “metropolitan residence” (OR 3.048, 95% CI 1.419–6.548). Among a total of 373 maternity HCPs, 210 (56.3%) routinely recommended pertussis vaccination, but 21.7% of the total maternity HCP participants did not know the maternal Tdap guideline. The independent factors affecting routine recommendation were the awareness of guideline (OR 9.771, 95% CI 5.227–18.265, p

Background: The intention of Chinese people older than age 5 to accept the pertussis vaccination is unknown, which is important for the future design of an effective pertussis vaccination program in China. Method: We conducted a cross-sectional survey among people older than age 5 in China. A 24-item questionnaire was used to explore the determinants of intention to accept a pertussis vaccination, and for children and adolescents (≦15 years old), their guardian was required to help answer the questionnaire on their behalf. Univariate and multivariate logistic regression was used to analyze the influencing factors of intention. Results: A total of 3,041 individuals participated in our survey and 3025 completed the questionnaire, among which 1938 (64.07%) reported a positive intention to be vaccinated. A multiple logistic regression analysis revealed that the main positive factors for the intention to accept pertussis vaccination were younger age (Odd ratio [OR] 0.838, P

Aims The Centre for Health Protection of Hong Kong has issued a recommendation on pertussis vaccination during pregnancy to protect infants against pertussis. This study aimed to explore the knowledge, perceptions, and attitudes toward pertussis vaccination during pregnancy among pregnant women in Hong Kong. Methods This was a cross-sectional study conducted over a 6-week period from August 17 to September 30 2019 among pregnant women in an obstetrics department in a regional public hospital in Hong Kong. Information on participants' demographics, medical, and immunization history, their knowledge, perception and attitudes, toward pertussis vaccination during pregnancy were gathered. Point-biserial correlation coefficients were used to determine correlation between variables. Results Only 112 (24.6%) women knew that pertussis vaccination can be given during pregnancy and 53 (11.6%) recognized that antenatal pertussis vaccination should be given in each pregnancy. Despite poor knowledge on the vaccination, over 80% of women showed an intention to receive pertussis vaccination during pregnancy. Fifty-two (71.3%) women expressed that recommendations by healthcare professionals may alter their decision on vaccination uptake. The score in the knowledge section and the perception to the vaccination positively correlated with the intention to be vaccinated. Those who were given advice by healthcare professionals were more likely to indicate an intention to receive the vaccination. Conclusion Pregnant women in Hong Kong are likely to accept antenatal pertussis vaccination despite the poor knowledge on vaccination in pregnancy and antenatal pertussis vaccination. Recommendations by healthcare professionals are a key factor affecting women's decision on vaccination uptake.

Introduction: The Accelerated Development of Vaccine benefit-risk Collaboration in Europe (ADVANCE) public-private collaboration, aimed to develop and test a system for rapid benefit-risk monitoring of vaccines using healthcare databases in Europe. The objective of this proof-of-concept (POC) study was to test the feasibility of the ADVANCE system to generate incidence rates (IRs) per 1000 person-years and incidence rate ratios (IRRs) for risks associated with whole cell- (wP) and acellular- (aP) pertussis vaccines, occurring in event-specific risk windows in children prior to their pre-school-entry booster. Methods: The study population comprised almost 5.1 million children aged 1 month to

The Global Pertussis Initiative is an expert scientific forum that publishes consensus recommendations concerning pertussis for many regions of the world. Here, we give recommendations for the primary vaccination of infants in those countries where whole-cell pertussis (wP)- and acellular pertussis (aP)-containing combination vaccines are used in parallel. A selective literature review was performed concerning the influence on safety, immunogenicity, and effectiveness of mixing wP- and aP-containing vaccines for primary immunization of infants. In addition, local data were collected from various countries and the results discussed in a face-to-face meeting. Very few data addressing issues of mixing combination vaccines were identified, and no data were available concerning the effectiveness or duration of protection. It was also found that pharmacovigilance data are scarce or lacking in those countries where they would be needed the most. We then identified frequent problems occurring in low- and middle-income countries (LMICs) where both vaccine types are used. Relying on local knowledge, we give practical recommendations for a variety of situations in different settings. Specific needs for additional data addressing these issues were also identified. International bodies, such as the World Health Organization (WHO), as well as vaccine producers should try to find ways to highlight the problems of mixing wP- and aP-containing combination vaccines with robust data. Countries are urged to improve on their pharmacovigilance for vaccines. For practicing physicians, our recommendations offer guidance when wP- and aP-containing vaccines are used in parallel during primary immunization., Instituto de Biotecnologia y Biologia Molecular

Background Prenatal pertussis vaccination was introduced in 2012 in England and is primarily delivered through general practice. Since 2017 some maternity services are commissioned to offer it too. We aimed to describe the maternity service delivery of prenatal pertussis vaccination and its impact on vaccine uptake. Methods We described the proportion of maternity services in England commissioned to offer pertussis vaccination to pregnant women in 2017/18 and the proportion of women vaccinated in this setting using a self-administered survey of NHS commissioners. We categorised clinical commissioning groups (CCGs) in England into “implementing” and “non-implementing” pertussis vaccination in maternity services. We identified CCGs where vaccination data was reliably transferred from maternity services to primary care records (source of routine data on vaccine uptake) and among those compared changes in vaccine uptake in implementing vs non-implementing CCGs between March 2016 (before implementation) and March 2018 (after). Findings Of 141 maternity service units in England, 61% delivered prenatal pertussis vaccine in 2017/18. Of those 57.0% of maternity services immunized less than 10% of pregnant women and only 7.1% of maternity services immunized more than 40% of pregnant women. Between March 2016 and March 2018, coverage increased by 19.6% among non-implementing CCGs compared with 17.8% among all implementing CCGs (difference −2.2, p = 0.48) and 28.2% among implementing CCGs with reliable methods of data transfer (difference 8.6, p = 0.04). This difference translated to a difference of 1.6 percentage points in absolute terms. Interpretation Delivering pertussis vaccine through maternity services has a moderate but important impact on vaccine uptake. There is a need to improve data transfer on vaccines administered in maternity service units to primary care. Maternity services should offer the vaccine to improve coverage and thus optimise protection for young infants. Barriers to effective programme implementation should be investigated and addressed.

Background In October 2012, a maternal pertussis vaccination program was introduced in England for women between 28 and 32 weeks of pregnancy. In April 2016, the recommended optimal window was extended to 20–32 weeks to improve vaccine coverage and protect preterm infants. This study assesses the impact of offering maternal pertussis vaccination earlier in pregnancy on hospitalized infant pertussis cases. Methods Hospitalized pertussis cases ≤60 days old in England were extracted from Hospital Episode Statistics pre- and post-policy change. Data were linked to laboratory-confirmed cases, and clinical records were reviewed where cases were not matched. Maternal vaccine status of identified cases was established. Median hospital duration was calculated, and a competing risk survival analysis was undertaken to assess multiple factors. Results A total of 201 cases were included in the analysis. Of the 151 cases with reported gestational age, the number of hospitalizations among full-term infants was 60 cases pre-policy and 62 cases post-policy, respectively, while preterm cases declined from 20 to 9 (P = .06). Length of hospital stay did not differ significantly after the policy change. Significantly longer hospital stays were seen in cases aged 0–4 weeks (median of 3 more days than infants aged 5–8 weeks), premature infants (median of 4 more days than term infants), and cases with coinfections (median of 1 more day than those without coinfection). Conclusions The number of preterm infants hospitalized with pertussis in England was halved after the policy change and preterm infants were no longer overrepresented among hospitalized cases., This study evaluates the impact of offering pertussis vaccination earlier in pregnancy in the second trimester on hospitalized infant pertussis cases in England. We found a decline in hospitalizations in preterm infants from 20 (18.5%) to 9 (9.7%) (P = .06).

Objective: As the current recommendation of administering Tdap (tetanus-diphtheria-acellular pertussis) to all pregnant women has not been widely implemented in the United Arab Emirates (UAE), we aimed to ascertain the prevalence of pertussis seronegativity during pregnancy. Methods: IgG antibodies against Bordetella pertussis toxin (PT) were measured in 213 women attending the antenatal clinic at Oasis hospital, Al Ain, UAE. Results were compared by maternal age, nationality and gestational age with the Kruskal–Wallis test for IgG-PT levels and the Chi-squared test for serology status. Results: The mean age ± SD of the participants was 30.4 ± 5.6 years, mean gestational age ± SD of 25.5 ± 3.3 weeks. Serum concentration of IgG-PT

Background A suboptimal maternal vaccination coverage in 2017–18 has been reported in Italy. The study aims were to (i) assess changes in maternal influenza and tetanus, diphtheria and acellular pertussis vaccination coverage during 2018–19 influenza season compared to the previous season (ii) estimate influenza vaccine coverage among maternal care providers (MCPs) and (iii) explore the characteristics of vaccine delivery to pregnant women. Methods We conducted a cross-sectional survey among pregnant women and MCPs about influenza and pertussis immunization during pregnancy. We also collected information regarding prenatal care characteristics and vaccine delivery among four centers in Italy. Results We recruited 483 pregnant women and 452 MCPs. The influenza and pertussis vaccine uptake among pregnant women for the season 2018–19 was 14.9% and 60.9%, respectively. MCPs’ influenza vaccine uptake was 33.6%. Knowing that the flu vaccine was safe for mothers and their infants and being vaccinated in the previous influenza season were associated with higher vaccine uptake. Regarding pertussis, being a housewife was associated to lower vaccine uptake, while knowing the vaccine is effective and safe for mothers and newborns were associated with higher pertussis vaccine uptake. The single most important factor associated to higher coverage of both influenza and pertussis vaccines was receiving a health-care provider’s vaccine advice. Most pregnant women (69.4%) stated that they preferred to be vaccinated in their same prenatal care setting. Conclusions Receiving a health-care provider’s vaccine advice and the availability of vaccines during prenatal care visits might improve vaccination coverage among pregnant women.

BackgroundInterventions to mitigate coronavirus disease 19 (COVID-19) pandemic may impact other respiratory diseases such as pertussis. We aimed to study the course of pertussis in France over an 8-year period and its association with COVID-19 mitigation strategies, using multiple nationwide data sources.MethodsWe analyzed the number of French pertussis cases between 2013 and 2020, using the PCR test results from nationwide outpatient laboratories (Source 1) and the pediatric network of 41 hospitals (Source 2), and using the reports of an office-based pediatric national network (Source 3). We conducted a quasi-experimental interrupted time-series analysis, relying on negative binomial regression models. The models accounted for seasonality, long-term cycles, and secular trend, and included a binary variable for the first national lockdown (ordered on March 16, 2021).ResultsWe identified 19,039 cases of pertussis from the three data sources during the study period. There was a significant decrease of pertussis cases following the implementation of mitigation measures, with adjusted incidence rate ratios of 0.102 (95% CI 0.040-0.256) and 0.216 (95% CI 0.071-0.656) for Source 1 and Source 2, respectively. The association was confirmed in Source 3 (median of 1 [IQR 0-2] vs. 0 [IQR 0-0] pertussis cases per month before and after lockdown, respectively, p=0.0048).ConclusionThe drastic reduction of outpatient and hospitalized cases of pertussis strongly suggests an impact of COVID-19 mitigation measures and their consequences on pertussis epidemiology. Pertussis vaccination recommendations should be carefully followed, and disease monitoring should be continued to detect any resurgence after relaxation of mitigation measures.FundingThere was no specific funding for the study.

Background: Bordetella pertussis, a highly contagious respiratory. Notably, the resurgence of pertussis has recently been associated with the lacking production of vaccine virulence factors. This study aimed to screen pertactin (Prn) and filamentous hemagglutinin (Fha) production in Iran with 50 years' whole cell vaccine (WCV) immunization program. Methods: Overall, 130 B. pertussis isolates collected from Pertussis Reference Laboratory of Iran during 2005-2018. Real-time PCR was performed by targeting IS481, ptxP, IS1001 and IS1002 for species confirmation of B. pertussis. Western-blot was used to evaluate the expression of virulence factors (pertactin and filamentous hemagglutinin). Results: All tested B. pertussis isolates expressed Prn and all except two isolates expressed Fha. We have sequenced genomes of these strains and identified differences compared with genome reference B. pertussis Tohama I. Conclusion: Many countries reporting Prn and Fha-deficiency due to acellular vaccine (ACV) pressure. Our results demonstrate in a country with WCV history, Fha-deficient isolates may rise independently. However, Prn-deficient isolates are more under the ACV pressure in B. pertussis isolates. Continues surveillance will provide a better understanding of the effect of WCV on the evolution of the pathogen deficiency.

Previous studies from low-resource countries have highlighted concerns surrounding non-specific effects of whole-cell pertussis vaccination, particularly in females. We sought to examine the effects of sex and birth weight on health services utilization following first exposure to whole-cell pertussis vaccine. Using a self-controlled case series design and by calculating relative incidence ratios (RIRs), we compared the relative incidence of emergency department visits and/or hospital admissions between sexes and between birth weight quintiles. Females had a higher relative incidence of events following vaccination compared to males (RIR = 1.13, 95% CI: 0.99, 1.30), which persisted after adjustment for birth weight (RIR = 1.12, 95% CI: 0.97, 1.28). We also observed a trend of increasing relative incidence of events over decreasing quintiles of birth weight; infants in the lowest quintile had a 26% higher relative event rate compared to the highest quintile, which was robust to adjustment for sex (Unadjusted RIR = 1.26, 95% CI: 1.01, 1.56; Adjusted RIR = 1.23, 95% CI: 0.99, 1.53). The risk of all-cause health services utilization immediately following vaccination, was elevated in female infants and infants having lower birth weight. Further study is warranted to determine if vaccine dosing should take infant weight into account.

Over the course of this project, we utilized pharmacists at 159 community pharmacies in Nebraska and Iowa to administer vaccinations to adults 19 years of age or older with the objective of improving immunization rates in both states. We implemented a pharmacy-based technology platform and partnered with public health via the state immunization registries of both states to ensure that immunizations provided at the pharmacy were transmitted to the statewide registry, for which reporting is currently voluntary for health care providers. After using the technology platform for one year, an increase of immunization rates for influenza, herpes zoster, and pertussis vaccination rates by 37%, 12%, and 74%, respectively, was recorded in comparison to the prior year numbers. However, there was about 16% decrease in vaccination rates for pneumococcal vaccine. For the first time, the project’s participating pharmacies in Nebraska reported immunization counts to their state’s immunization registries. This project leveraged community pharmacies as healthcare destinations to achieve further gains in increasing immunization rates, improving the health of adults, and creating a community-wide network for prevention.

ZusammenfassungKeuchhusten wird bei Patienten nach Erfahrung des Autors häufig übersehen, da viele Ärzte anscheinend nicht mehr mit dem Auftreten der Erkrankung rechnen. Die Inzidenz des Keuchhustens ist jedoch ansteigend, und selbst eine erfolgte Impfung oder eine früher durchgemachte Erkrankung sind keine Garantie für eine lang andauernde Schutzwirkung. Ziel dieses Artikels ist daher, einen Überblick über die Erkrankung, ihre Diagnostik und Therapiemöglichkeiten zu geben, sowie auf mögliche Gründe hinzuweisen, warum der Keuchhusten oft übersehen wird. Anhand mehrerer Fälle aus meiner Praxis wird schließlich die homöopathische Behandlung des Keuchhustens näher betrachtet.

Introduction: The objective was to estimate the effectiveness of maternal pertussis vaccination in protecting infants aged < 2 months. Methods: We performed a case-control study. Laboratory-confirmed cases aged < 8 weeks at disease onset were identified and 2-4 matched-controls born within +/- 15 days of the case were included. Information was obtained from healthcare providers and maternal interviews. Odds ratios (OR) were calculated using multivariable conditional logistic regression. Vaccine effectiveness (VE) was estimated as (1 - OR) x 100%. Results: 47 cases and 124 controls were studied. The mean age (in days) (39.8 +/- 12.7 vs. 40.8 +/- 13.2), weeks of gestation (38.8 vs. 39.1, p = 0.43) and mean birth weight (3.309 vs. 3.253 kg, p = 0.55) were comparable between cases and controls. Mothers of cases were less frequently vaccinated in the third trimester (59.6% vs. 83.9%, p < 0.001). The VE of maternal vaccination in pregnancy was 88.0% (95%CI 53.8%-96.5%), and was slightly higher in those vaccinated before the 32nd week of gestation (88.5% vs 87.8%). Conclusion: Pertussis vaccination in pregnancy is very effective in reducing pertussis in children aged < 2 months. Vaccination before and after the 32nd week of pregnancy are equally effective in reducing the risk of pertussis. (c) 2021 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Altres ajuts: acords transformatius de la UAB Aims and Objectives: To identify how pregnant women perceive pertussis and influenza and the factors that influence their decision to be vaccinated. Background: Suffering from influenza during pregnancy increases complications in the pregnant woman, foetus and newborn. Pertussis in children under six months of age causes severe complications. Maternal vaccination against influenza and pertussis is effective and safe. However, vaccination rates are insufficient. Design: We conducted a qualitative descriptive study, using semi-structured interviews. This research adheres to the COREQ guidelines and checklist. Methods: We carried out 18 semi-structured face-to-face interviews with pregnant women, using intentional sampling and thematic analysis. Results: We identified an overarching theme, 'factors that influenced participants' decision to be vaccinated or not', which was composed of four subthemes that were in turn made up of 12 categories. The factors that influenced participants' decision to be vaccinated against influenza and pertussis were related to their knowledge of and their perception of risk for these diseases. Participants perceived the risk of pertussis to be greater, and they focused their concern on the newborn. The recommendations and convictions of nurse-midwives were the most important factors encouraging vaccination. Participants trusted their nurse-midwives and most reported that they would have been vaccinated if their midwife had recommended it. Other factors were linked to lack of information, fear and concerns about economic interests. Conclusions: The convictions and actions of the nurse-midwife in recommending vaccination to pregnant women are decisive. Strategies to improve vaccination rates should be directed to helping health professionals understand how their practice affects the final decision of pregnant women. Relevance to clinical practice: Understanding the factors that limit vaccination rates among pregnant women provides valuable information to nurse-midwives that can help to improve vaccination strategies and practices. Increased maternal vaccination rates would reduce morbidity and mortality among pregnant women and newborns.

The Accelerated Development of VAccine benefit-risk Collaboration in Europe (ADVANCE), a public-private consortium, implemented and tested a distributed network system for the generation of evidence on the benefits-risks of marketed vaccines in Europe. We tested the system by estimating the incidence rate (IR) of pertussis and pertussis-related complications in children vaccinated with acellular (aP) and whole-cell (wP) pertussis vaccine. Data from seven electronic databases from four countries (Denmark: AUH and SSI, Spain: SIDIAP and BIFAP, UK: THIN and RCGP RSC and Italy: Pedianet) were included in a retrospective cohort analysis. Exposure was defined as any pertussis vaccination (aP or wP). The follow-up time started 14 days after the first dose. Children who had received any pertussis vaccine from January 1990 to December 2015 were included (those who switched type, or had unknown type were excluded). The outcomes of interest were confirmed or suspected pertussis and pertussis-related pneumonia and generalised convulsions within one month of pertussis diagnosis and death within three months of pertussis diagnosis. The cohort comprised 2,886,367 children ≤5 years of age. Data on wP and aP vaccination were available in three and seven databases, respectively. The IRs (per 100,000 person-years) for pertussis varied largely and ranged between 0.15 (95% CI: 0.12; 0.19) and 1.15 (95% CI: 1.07; 1.23), and the trends over time was consistent with those observed from national surveillance databases for confirmed pertussis. The pertussis IRs decreased as the number of wP and aP vaccine doses increased. Pertussis-related complications were rare (89 pneumonia, 7 generalised convulsions and no deaths) and their relative risk (vs. non-pertussis) could not be reliably estimated. The study demonstrated the feasibility of the ADVANCE system to estimate the change in pertussis IRs following pertussis vaccination. Larger sample sizes would provide additional power to compare the risk for complications between children with and without pertussis. The feasibility of vaccine-type specific effectiveness studies may be considered in the future.

Background: Whole-cell pertussis (wP) vaccine administration is still advocated for children under 7 years of age in Iran. However, there is no recommendation for the administration of a dose of tetanus, diphtheria, and acellular pertussis (Tdap) vaccine to childbearing age/pregnant women in the Iranian vaccination program and it has increased the risk of infection through waning immunity during women’s childbearing age life. The study aimed to assess the levels of anti- Bordetella pertussis antibodies in childbearing age women of different ages in Iran. Methods: A cross-sectional study was conducted on a total number of 360 childbearing age women divided into six age groups, with 5-year intervals from 15 to 45 years old, in 2018–2019. Then, the levels of immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) antibodies against B. pertussis were evaluated using enzyme-linked immunosorbent assay (ELISA). The IBM SPSS Statistics software (version 16.0) (SPSS Inc., Chicago, IL, USA) was used for data analysis. Results: The mean age of the participants was 30.01 ± 8.35 years (range 14–45 years). All the cases were IgM negative, but two IgA-positive individuals (in the age groups of 14–19 and 30–34 years) were reported. Overall, 239 (66.4%) cases were IgG positive. The mean age of IgG-positive cases was 30.37 ± 8.37 years. The IgG-positive cases were mostly in the age groups of 30–34 and 35–39 years [43 (71.1%)]. The odds of IgG positivity were 1.97. The highest odds of IgG positivity were seen in 30–34 and 35–39 years groups (2.52) and the lowest odds were seen in the 20–24 and 25–29 years groups (1.60). Using the Jonckheere–Terpstra test, the increasing trend of IgG changes in different age groups was not statistically significant (Tπ=5.78, p = 0.09). Conclusion: The infants of women of childbearing age might be prone to pertussis in countries using the wP vaccination schedule. It is suggested to administer a dose of Tdap to women before or during pregnancy to increase the immunity of their infants against this disease during early infancy.

The Accelerated Development of VAccine beNefit-risk Collaboration in Europe (ADVANCE) is a public–private collaboration aiming to develop and test a system for rapid vaccine benefit-risk monitoring using existing European healthcare databases. Incidence rate (IR) estimates of vaccination-associated adverse events that are needed to model vaccination risks can be calculated from existing healthcare databases when vaccination (exposure) data are available. We assessed different methods to derive IRs in risk periods following vaccination when exposure data are missing in one database, using estimated IRs and IRRs from other databases for febrile seizures, fever and persistent crying. IRs were estimated for children aged 0–5 years in outcome-specific risk and non-risk periods following the first dose of acellular pertussis (aP) vaccination in four primary care databases and one hospital database. We compared derived and observed IRs in each database using three methods: 1) multiplication of non-risk period IR for database i by IR ratio (IRR) obtained from meta-analysis of IRRs estimated using the self-controlled case-series method, from databases other than i; 2) same method as 1, but multiplying with background IR; and 3) meta-analyses of observed IRs from databases other than i. IRs for febrile seizures were lower in primary care databases than the hospital database. The derived IR for febrile seizures using data from primary care databases was lower than that observed in the hospital database, and using data from the hospital database gave a higher derived IR than that observed in the primary care database. For fever and persistent crying the opposite was observed. We demonstrated that missing IRs for a post-vaccination period can be derived but that the type of database and the method of event data capture can have an impact on potential bias. We recommend IRs are derived using data from similar database types (hospital or primary care) with caution as even this can give heterogeneous results.

Pertussis is quite common in adolescents and adults, but it is especially dangerous in new-borns. The national immunization plan (NIP) 2017-2019 recommended a Tdap booster for every pregnancy at 28-36 weeks, but adherence is still far from the optimal level. This work aims to evaluate the effectiveness of a dedicated pathway organized by the department of prevention to improve the Tdap coverage among pregnant woman attending antenatal class. The women attending from November 2019 to October 2019 the public antenatal class organized by the local health authority have been evaluated for their Tdap coverage in pregnancy. From May 2019, public health experts have been involved for 30 minutes during the first lesson to explain the NIP with a focus on vaccination in pregnancy. Then the eligible women (28-36 weeks not yet vaccinated) who voluntarily agree were accompanied to the ambulatory to be vaccinated. Pre-post Tdap vaccination coverage and pregnancy weeks at vaccination have been evaluated respectively by chi2 and t-test. 90 pregnant women have been included in the study. Their mean age was 32.3 (SD 5.2) and the overall Tdap coverage was 44.4%. The Pre-post Tdap coverage was 26.7%(12/45) before May 2019 and 62.2% (28/45) after the introduction of the new pathway (p = 0.001). 50% of the vaccinated women decided to receive the booster the same day of the antenatal lesson, while the remaining 50% delayed the vaccination till a maximum of 30 days. We observed a clinical, but not statistically, significant anticipation in the pregnancy week in which they received Tdap booster (32.4 weeks before and 31.3 after May 2019; p = 0.150). The introduction of a short intervention on vaccination in the antenatal class followed by the opportunity to receive the booster in a dedicated time and without waiting list significantly improved the Tdap coverage in pregnancy. This study encourages the cooperation among the different public health actors involved in the field of antenatal care. Key messages Antenatal class represents a great opportunity to improve vaccine confidence in pregnant women. Intervention aimed to ameliorate vaccine convenience could improve Tdap coverage in pregnancy.

BACKGROUND: Maternal Pertussis Vaccination (MPV) during pregnancy became part of the National Immunization Program in the Netherlands late 2019. This study aims to identify social-psychological factors associated with MPV acceptance among Dutch women to add to the current understanding of vaccine hesitancy worldwide, and to inform the development of communication and information campaigns about MPV.METHODS: We conducted a cross-sectional study using an online survey among 611 women (174 pregnant women, 205 women who had given birth in the past two years and 232 women of 20-35 years old). The primary and secondary outcomes were vaccination intention and attitude towards MPV, respectively. Pearson's correlation and regression analyses were used to examine social-psychological and socio-demographic determinants of the outcomes.RESULTS: Vaccination intention was most explained by attitudes towards MPV, beliefs about safety, moral norm and the belief about the effectiveness of MPV (R2 = 0.79). Other factors associated were injunctive norm, anticipated regret of vaccinating, and decisional certainty. Attitudes towards MPV were further explained by descriptive norm, risk perceptions of side effects, and risk perceptions of the baby getting pertussis when not vaccinating, and fear of MPV and of the disease (R2 = 0.76). Finally, pregnant women had a significantly lower intention and less positive attitude towards MPV than non-pregnant women.CONCLUSIONS: Communication about MPV should address the most important determinants of MPV intention and attitude, i.e. beliefs about safety and effectiveness and moral norms. Furthermore, such information may benefit from taking into account affective feelings of pregnant women such as anticipated regret and fear towards MPV. Further research could explore this. The timing of communication about MPV can be important as determinants of MPV acceptance may vary depending on pregnancy status.

Immunity following natural infection or immunization may wane, increasing susceptibility to infection with time since infection or vaccination. Symptoms, and concomitantly infectiousness, depend on residual immunity. We quantify these phenomena in a model population composed of individuals whose susceptibility, infectiousness, and symptoms all vary with immune status. We also model age, which affects contact, vaccination and possibly waning rates. The resurgences of pertussis that have been observed wherever effective vaccination programs have reduced typical disease among young children follow from these processes. As one example, we compare simulations with the experience of Sweden following resumption of pertussis vaccination after the hiatus from 1979 to 1996, reproducing the observations leading health authorities to introduce booster doses among school-aged children and adolescents in 2007 and 2014, respectively. Because pertussis comprises a spectrum of symptoms, only the most severe of which are medically attended, accurate models are needed to design optimal vaccination programs where surveillance is less effective. (C) 2020 The Authors. Published by Elsevier Ltd. American Institute of Mathematics (AIM); National Science Foundation (NSF)National Science Foundation (NSF) [DMS-1814545]; Natural Sciences and Engineering Research Council of Canada (NSERC)Natural Sciences and Engineering Research Council of Canada; York University Research Chair Program; SQuaRE grants; IR/D program The authors acknowledge the generous support of the American Institute of Mathematics (AIM) via workshop and SQuaRE grants. ZF acknowledges support from the National Science Foundation (NSF) via DMS-1814545 and the IR/D program. JMH acknowledges support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the York University Research Chair Program. The authors thank Patrick Olin and Birger Trollfors for helpful discussions about pertussis and Tiia Lepp for observations from enhanced pertussis surveillance in Sweden. The authors also thank John Edmunds for permitting them to use observations from the PolyMod study.

Studies in countries with high immunisation coverage suggest that the re-emergence of pertussis may be caused by a decreased duration of protection resulting from the replacement of whole-cell pertussis vaccine (WPV) with the acellular pertussis vaccine (APV). In China, WPV was introduced in 1978. The pertussis vaccination schedule advanced from an all-WPV schedule (1978–2007), to a mixed WPV/APV schedule (2008–2009), then to an all-APV schedule (2010–2016). Increases in the incidence of pertussis have been reported in recent years in Jinan and other cities in China. However, there have been few Chinese-population-based studies focused on the impact of schedule changes. We obtained annual pertussis incidences from 1956 to 2016 from the Jinan Notifiable Conditions Database. We used interrupted time series and segmented regression analyses to assess changes in pertussis incidence at the beginning of each year, and average annual changes during the intervention. Pertussis incidence decreased by 1.11 cases per 100 000 population (P= 0.743) immediately following WPV introduction in 1978 and declined significantly by 1.21 cases per 100 000 population per year (P< 0.0001) between 1978 and 2001. Immediately after APV replaced the fourth dose of WPV in 2008, the second and third doses in 2009, then replaced all four doses in 2010, pertussis incidence declined by 1.98, 1.98 and 1.08 cases per 100 000 population, respectively. However, the results were not statistically significant. There were significant increasing trends in pertussis incidence after APV replacements: 1.63, 1.77 and 1.78 cases/year in 2008–2016, 2009–2016 and 2010–2016, respectively. Our study shows that the impact of an all-WPV schedule may be less than the impacts of the sequential WPV/APV schedules. The short-term impact of APV was better than that of WPV; however, the duration of APV-induced protection was not ideal. The impact and duration of protective immunity resulting from APVs produced in China need further evaluation. Further research on the effectiveness of pertussis vaccination programme in Jinan, China is also necessary.

The reemergence of pertussis in the last two decades led to the introduction of adolescents and adults immunization strategies of tetanus–diphtheria–acellular pertussis vaccines (Tdap) in several countries. The health authorities must consider economic aspects when deciding to recommend and fund new programs. Here we present a systematic review of worldwide full economic evaluations of pertussis vaccination targeting adolescents or adults published from 2000. Studies were identified by searching MEDLINE, Excerpta Medica, CRD, and Lilacs databases. Twenty-seven economic evaluations of different strategies with Tdap were identified. Booster vaccination for adolescents and adults were the most frequent, followed by cocooning and pregnant women vaccination. Strategies performance varied considerably among different studies. Assumptions regarding underreporting correction, herd protection and vaccine coverage were crucial to cost-effectiveness results. Understanding the model and the parameters used is essential to understand the results, and identify the major issues important to public health decisions.

Key Russian experts representing applied medicine, scientific and educational organizations related to the vaccination hold the meeting on June 13 in Moscow. The main issue of the agenda was the discussion of the new approaches to vaccination of pertussis. It was noted that it is still a topical question for public health worldwide including Russia. The experts comprised the list of the unresolved questions related to pertussis surveillance and prevention. The most important fact is a continuing spread of pertussis due to the decrease of immune response 5–7 years after any type of pertussis vaccine, and a growing number of the people who have not suffered from pertussis before. Increase of pertussis incidence among one year old children as well as schoolchildren and adults attests for the circulation of pathogen and continuous spread of the disease. This makes necessary an introduction of additional pertussis vaccination boosters. The data of epidemiological surveillance in the countries which already introduced the second booster against pertussis for 4–7 year old children (more than 50 countries) shows essential epidemiological effect and decrease of pertussis incidence at the age from 4 to 10 years old, and has already demonstrated indirect protection for one year old children. The experts made final recommendations for Russia regarding the improvement of pertussis surveillance on regional and federal levels. Certain possible strategies of anti-pertussis vaccination were offered in accordance with the developing vaccines and technologies.

Pertussis vaccination policy varies across Europe, not only in the type of vaccine – whole cell (wP) vs. acellular (aP1/2/3/5) – but also in the schedule and recommendation for parents. This study aims to investigate the determining factors for the type of vaccine, immunization schedule and maternal immunization recommendation. From March to May 2019, experts in national health agencies and major academic or research institutions from Denmark, France, Poland, Sweden and the UK were invited to a semi-structured interview. Thematic analysis was performed on the transcripts using a codebook formulated by 3 coders. Inter-coder agreement was assessed. Fifteen expert interviews were conducted. The identified driving factors for pertussis vaccine policy were classified into three domains: scientific factors, sociological factors, and pragmatic factors. The determining factors for the type of vaccine were prescriber’s preference, concern of adverse events following immunization (AEFI), effectiveness, and consideration of other vaccine components in combined vaccines. The determining factors for infant schedule were immunity response and the potential to improve coverage and timeliness. The determining factors for maternal immunization were infant mortality and public acceptability. To conclude, socio-political and pragmatic factors were, besides scientific factors, important in determining the vaccine type, schedule of childhood immunization and recommendations for parents.

Introduction The Accelerated Development of VAccine beNefit-risk Collaboration in Europe (ADVANCE) is a public-private collaboration aiming to develop and test a system for rapid benefit-risk (B/R) monitoring of vaccines, using existing healthcare databases in Europe. The objective of this paper was to assess the feasibility of using electronic healthcare databases to estimate dose-specific acellular pertussis (aP) and whole cell pertussis (wP) vaccine coverage. Methods Seven electronic healthcare databases in four European countries (Denmark (n = 2), UK (n = 2), Spain (n = 2) and Italy (n = 1)) participated in this study. Children were included from birth and followed up to age six years. Vaccination exposure was obtained from the databases and classified by type (aP or wP), and dose 1, 2 or 3. Coverage was estimated using period prevalence. For the 2006 birth cohort, two estimation methods for pertussis vaccine coverage, period prevalence and cumulative incidence were compared for each database. Results The majority of the 2,575,576 children included had been vaccinated at the country-specific recommended ages. Overall, the estimated dose 3 coverage was 88–97% in Denmark (birth cohorts from 2003 to 2014), 96–100% in the UK (2003–2014), 95–98% in Spain (2004–2014) and 94% in Italy (2006–2007). The estimated dose 3 coverage per birth cohort in Denmark and the UK differed by 1–6% compared with national estimates, with our estimates mostly higher. The estimated dose 3 coverage in Spain differed by 0–2% with no consistent over- or underestimation. In Italy, the estimates were 3% lower compared with the national estimates. Except for Italy, for which the two coverage estimation methods generated the same results, the estimated cumulative incidence coverages were consistently 1–10% lower than period prevalence estimates. Conclusion This study showed that it was possible to provide consistent estimates of pertussis immunisation coverage from the electronic healthcare databases included, and that the estimates were comparable with the national estimates.

Background An online education programme was developed to support midwives and maternity staff to implement the New South Wales antenatal pertussis vaccination programme from March 2015. Aims To determine if an educational programme met the needs of midwives and maternity staff to conduct an immunisation appointment confidently with a pregnant woman. Methods Pre- and post-surveys were conducted with learners completing the programme. Findings Before completing the programme, 57% of respondents reported feeling ‘confident’ or ‘very confident’ in conducting a vaccination encounter with a pregnant woman. This increased to 94.1% after completion of the programme. Conclusion The education programme met the needs of midwives and maternity staff in New South Wales. An informed and confident maternity workforce will increase vaccine uptake in pregnant women and ensure that pertussis vaccination is incorporated consistently into routine antenatal care, to protect vulnerable infants from life-threatening diseases such as pertussis and influenza.

INTRODUCTION. After the introduction of compulsory pertussis vaccination in Poland in 1960, there was a sharp decline in the incidence of this disease. For several years, however, an increase in the number of reported cases has been observed. In 2015 and 2016, the incidence was 12.9 and 17.8 per 100 000 population, respectively (1). The year 2017 can be treated as an inter-epidemic year in which there was a significant decrease (by 55.1%) incidence to 8.0 per 100 000 population compared to the previous year. Pertussis who are still old who may be the source of infection for non-immunized or not fully immunized newborns and infants are still a high percentage. Vaccination in accordance with the current calendar remains the most effective strategy for preventing illness. In our country, research is being carried out to optimize pertussis vaccination schedules using both whole-cell and acellular vaccines. OBJECTIVES. The aim of the study is to assess the epidemiological situation of pertussis in Poland in 2017 compared to the situation in previous years, with particular emphasis on assessing the vaccination status of children against pertussis. MATERIAL AND METHODS. The assessment of the epidemiological situation of pertussis in Poland was carried out on the basis of the results of the analysis of individual reports of suspected pertussis cases sent to NIZP-PZH by provincial sanitary-epidemiological stations and data from the bulletin ‘Infectious diseases and poisoning in Poland in 2017’ (2) and the bulletin ‘Protective vaccinations in Poland in 2017’ (3). RESULTS. In 2017, 3 061 pertussis cases were recorded. The incidence was 8.0 per 100 000 population and was 55% lower than in the previous year (17.8). The highest incidence of pertussis occurred in persons in the age group 0-4 years (37.0), and high in children and adolescents aged 5-9 and 10-14 years - 21.4 and 25.7 per 100 000 population. From 3 061 pertussis patients, 762 people (i.e. 25%) were hospitalized. In 2017, no deaths from pertussis were reported. SUMMARY AND CONCLUSIONS. The number of pertussis cases observed in 2017 indicates the persistent circulation of bacteria in the environment and the persistent susceptibility of the population to infection. Still, the only effective strategy to reduce the number of cases of vaccination remains the use of vaccinations according to the current calendar and expert recommendations.

Background While recommendations to vaccinate adults against pertussis exist, information on uptake for adult tetanus-diphtheria-pertussis vaccine (Tdap) among older adults is limited. Methods We used data from the 45 and Up Study, a prospective cohort of adults aged ≥45 years who completed a questionnaire between 2012 and 2014 asking about pertussis vaccination. We evaluated Tdap uptake following a program providing free vaccine for adults in contact with young children between 2009 and 2012. Results Among 91,432 adults (mean age = 66.3 years, SD = 9.6), 3.1% (n = 2823) reported receiving Tdap prior to the program. This increased seven-fold to 21.8% (n = 19898) after the program finished. Tdap coverage was almost twice as high in women compared to men and among adults more likely to be grandparents than those not. Conclusion These findings suggest that funding for a targeted program can help to substantially increase vaccination coverage as well as decrease disparities in the uptake of Tdap in different sub-groups.

Infants are at the highest risk of severe complications - including death - as a result of pertussis infection. Controlling pertussis in this group has been challenging, particularly in those too young to be vaccinated. Following revised national recommendations in March 2015, the state of New South Wales, Australia, introduced a funded maternal vaccination campaign at 28 - 32 weeks of gestation using a 3-component tetanus-diphtheria-acellular pertussis vaccine (dTpa; Boostrix, GSK). This study aimed to assess the effectiveness of maternal vaccination and add to the growing body of evidence for this strategy.A 1:1 matched case-control study was conducted between 16 August 2015 and 17 August 2016. Cases were laboratory or doctor notified, laboratory confirmed (nucleic acid testing or culture) and aged6 months at onset. Each control infant was randomly selected from public hospital births in the same geographical area in the period up to 3 days before and after the case's birthdate. Odds ratios (OR) were calculated using conditional logistic regression. Vaccine effectiveness (VE) was calculated as 1 - OR.In total, 117 cases and 117 controls were recruited. The overall VE estimate was non-significantly protective for infants6 months old (VE 39%, 95% CI -12 to 66%). Higher VE was observed for infants3 months old (VE 69%, 95% CI 13-89%) and against hospitalisation (VE 94%, 95% CI 59-99%).Maternal pertussis vaccination with a 3-component acellular vaccine was found to be highly effective at preventing severe disease in infants, but was less effective at preventing disease which did not require hospitalisation. The overall VE reported in this study was lower than in prior studies and suggests that maternal vaccination, while an effective strategy at preventing severe pertussis, is less effective at protecting against infection or mild disease.

SUMMARYThis study assessed variation in coverage of maternal pertussis vaccination, introduced in England in October 2012 in response to a national outbreak, and a new infant rotavirus vaccination programme, implemented in July 2013. Vaccine eligible patients were included from national vaccine coverage datasets and covered April 2014 to March 2015 for pertussis and January 2014 to June 2016 for rotavirus. Vaccine coverage (%) was calculated overall and by NHS England Local Team (LT), ethnicity and Index of Multiple Deprivation (IMD) quintile, and compared using binomial regression. Compared with white-British infants, the largest differences in rotavirus coverage were in ‘other’, white-Irish and black-Caribbean infants (−13·9%, −12·1% and −10·7%, respectively), after adjusting for IMD and LT. The largest differences in maternal pertussis coverage were in black-other and black-Caribbean women (−16·3% and −15·4%, respectively). Coverage was lowest in London LT for both programmes. Coverage decreased with increasing deprivation and was 14·0% lower in the most deprived quintile compared with the least deprived for the pertussis programme and 4·4% lower for rotavirus. Patients’ ethnicity and deprivation were therefore predictors of coverage which contributed to, but did not wholly account for, geographical variation in coverage in England.

Background Persistent cough is a very distressing condition. It may be due to infectious agents, including Bodetella pertussis. In this case, associated symptoms are frequently different from typical pertussis (PT) cases and diagnosis is difficult and delayed. In this study, the role of B. pertussis infection as cause of persistent cough in school-children and adolescents and the protective role of previously administered PT vaccine doses was evaluated. Methods Healthy 7- to 17-year-old children with cough lasting from 2 to 8 weeks were enrolled. Excluded were the patients who had received the preschool booster (PSB) PT vaccine less than one year before the cough onset. At enrollment, a nasopharyngeal swab and an oral fluid sample were obtained to seek pertussis infection by detection of B. pertussis DNA in the nasopharynx using PCR and/or an elevated titer of anti-pertussis toxin IgG in oral fluid using an IgG antibody-capture enzyme-linked immunosorbent assay. Saliva determination of anti-PT toxin IgG was used because it acts as a surrogate for anti-PT toxin IgG serology. Results Among 96 patients, pertussis was diagnosed in 18 (18.7%; 95% CI 11.5–28.0). In 2 children with cough lasting 2 weeks, confirmation was based on the detection of B. pertussis; in 13 cases, with cough lasting 4–7 weeks, PT was diagnosed because there were high anti-PT IgG titers in oral fluid; and in 3 cases, with cough lasting 3 weeks, PT was diagnosed due to positivity for both tests. In 15 children, the disease occurred despite PSB administration. In 2 cases, PT diagnosis was made only 16 and19 months after booster injection, whereas in other 13 cases infection emerged after a longer period. However, in eight cases disease occurred less than 5 years after vaccine administration. Conclusion This study demonstrates that about 20% of persistent cough in children is due to PT. In case of persistent cough, this has to be considered to prescribe an effective therapy. Moreover, the study confirms that protection evoked by PT vaccine rapidly wanes and that schoolchildren may return to be PT susceptible after few year of the officially recommended PSB dose. If confirmed, these findings might lead to anticipate presently recommended PT vaccine dose for adolescents. Disclosures All authors: No reported disclosures.

Key Points Question Are undervaccination and delay in vaccination with diphtheria-tetanus–acellular pertussis (DTaP) vaccine associated with pertussis risk in infants and young children? Findings In this population-based cohort study of 316 404 children, those who were undervaccinated for the primary series, second-year booster, and preschool booster of the DTaP vaccine had 4.8-fold, 3.2-fold, and 4.6-fold higher pertussis risk, respectively, compared with fully vaccinated children. Doses administered with a short delay were not associated with pertussis risk. Meaning These results suggest that young children should receive DTaP doses in an age-appropriate and timely fashion as recommended by the Centers for Disease Control and Prevention for best protection against childhood pertussis., This cohort study assesses whether undervaccination or a delay in vaccination with the diphtheria-tetanus–acellular pertussis (DTaP) vaccine is associated with pertussis risk in infants and young children., Importance In most countries, the diphtheria-tetanus–acellular pertussis (DTaP) vaccine is administered as a 3-dose infant series followed by additional booster doses in the first 5 years of life. Short-term immunity from the DTaP vaccine can depend on the number, timing, and interval between doses. Not receiving doses in a timely manner might be associated with a higher pertussis risk. Objective To examine the association between number and timeliness of vaccine doses and age-specific pertussis risk. Design, Setting, and Participants This population-based, retrospective cohort study used Washington State Immunization Information System data and pertussis surveillance data from Public Health Seattle and King County, Washington. Included participants were children aged 3 months to 9 years born or living in King County, Washington, between January 1, 2008, and December 31, 2017. Data were analyzed from June 30 to December 1, 2019. Exposures Being undervaccinated (receiving fewer than recommended doses at a given age) or delayed vaccination (not receiving doses within time frames recommended by Centers for Disease Control and Prevention). Main Outcomes and Measures Suspected, probable, and confirmed pertussis diagnosis. Results A total of 316 404 children (median age, 65.2 months [interquartile range, 35.3-94.1 months]; 162 025 boys [51.2%]) as of December 31, 2017, with 17.4 million person-months of follow-up were included in the analysis. A total of 19 943 children (6.3%) had no vaccines recorded in the Immunization Information System, 116 193 (36.7%) received a vaccine with a delay, and 180 268 (56.9%) were fully vaccinated with no delay. Delayed vaccination and undervaccination rates were higher for older children (17.6% delayed or undervaccinated at age 2 months for dose 1 at 3 months vs 41.6% at age 5 years for dose 5) but improved for successive birth cohorts (52.2% for 2008 birth cohort vs 32.3% for 2017 birth cohort). Undervaccination was significantly associated with higher risk of pertussis for the 3-dose primary series (adjusted relative risk [aRR], 4.8; 95% CI, 3.1-7.6), the first booster (aRR, 3.2; 95% CI, 2.3-4.5), and the second booster (aRR, 4.6; 95% CI, 2.6-8.2). However, delay in vaccination among children who received the recommended number of vaccine doses was not associated with pertussis risk. Conclusions and Relevance The results of this cohort study suggest that undervaccination is associated with higher pertussis risk. Short delays in vaccine receipt may be less important if the age-appropriate number of doses is administered, but delaying doses is not recommended. Ensuring that children receive all doses of pertussis vaccine, even if there is some delay, is important.

Despite robust vaccination schedules and high vaccination rates, many countries, including the U.S., have seen large pertussis outbreaks with a shift in recent years in the distribution of disease burden towards adolescents and young adults. Areas covered: This perspective covers problems related to the increased incidence of pertussis among adolescents. Because the Tdap vaccine only protects against pertussis for 1-2 years after vaccination, we propose a new strategy which aims to optimize the benefit of Tdap in adolescents. Expert commentary: Current pertussis vaccination schedules are based on age and have not been effective at protecting adolescents and teenagers from pertussis outbreaks. An alternative to the current practice would be to take advantage of the cyclical nature of pertussis outbreaks. Rather than immunizing children and adolescent solely based on age regardless of risk of pertussis at that moment, perhaps we should consider a 'timed' Tdap. The goal would be to administer Tdap to susceptible adolescents and young adults during periods when there is a greater risk of being exposed to pertussis. This approach would optimize the use of an effective, but short-lived vaccine by maximizing protection at the time of increased risk.

BACKGROUND Despite high pertussis-containing vaccine coverage in the United States, children who are unvaccinated or not fully vaccinated remain susceptible to pertussis. Over multiple birth cohorts of incomplete vaccination, the number of children not immune to pertussis will accumulate because of factors such as age-specific vaccination status and dose-specific vaccine effectiveness. The total number of pertussis-susceptible children 0-23 months of age in the United States is unknown. METHODS Using data on age-specific pertussis-containing vaccine receipt among children evaluated in the 2013 National Immunization Survey (born between February 2011 and June 2012) and accounting for vaccine effectiveness and maternal transfer of antipertussis antibodies, we estimated the cumulative number of pertussis-susceptible children 0-23 months of age. RESULTS Of an estimated 7,905,672 children 0-23 months of age in the United States, we estimated that approximately 22% (1,716,429) are susceptible to pertussis. Age was a large factor in susceptibility, with 89% of children less than 2 months of age not immune to pertussis compared with 7% of children 21-23 months of age. In sensitivity analysis, increasing maternal pertussis vaccination coverage from 10% to 42% decreased susceptibility in children less than 2 months of age to 68%. When considering waning immunity after the fourth dose of vaccine, the herd protection threshold was no longer reached. CONCLUSIONS These estimates underscore the need to monitor age-specific pertussis vaccine coverage, to increase childhood and maternal pertussis vaccine coverage, to maintain population-level immunity and to prevent the spread of pertussis among young children.

In the mid-1990s, whole-cell pertussis (wP) vaccines were associated with local and systemic adverse events that prompted their replacement with acellular pertussis (aP) vaccines in many high-income countries. In the past decade, rates of pertussis disease have increased in children receiving only aP vaccines. We compared the immune responses to aP boosters in individuals who received their initial doses with either wP or aP vaccines using activation-induced marker (AIM) assays. Specifically, we examined pertussis-specific memory CD4+ T cell responses ex vivo, highlighting a type 2/Th2 versus type 1/Th1 and Th17 differential polarization as a function of childhood vaccination. Remarkably, after a contemporary aP booster, cells from donors originally primed with aP were (a) associated with increased IL-4, IL-5, IL-13, IL-9, and TGF-β and decreased IFN-γ and IL-17 production, (b) defective in their ex vivo capacity to expand memory cells, and (c) less capable of proliferating in vitro. These differences appeared to be T cell specific, since equivalent increases of antibody titers and plasmablasts after aP boost were seen in both groups. In conclusion, our data suggest that there are long-lasting effects and differences in polarization and proliferation of T cell responses in adults originally vaccinated with aP compared with those that initially received wP, despite repeated acellular boosters.

Key Clinical Message Household is responsible for a large percentage of pertussis infection in young infants. Japanese vaccine recommendation committee does not recommend any boosters for teens and pregnant women. Because of its high vaccine effectiveness, introduction of vaccination for pregnant women is high priority to prevent pertussis infection in young infants.

Objective In 2017, the Italian Ministry of Health issued the new 2017-19 National Plan of Vaccine Prevention and pregnant women were targeted to be vaccinated against influenza and pertussis. Our study aim was to assess the barriers and facilitators regarding maternal immunization acceptance among pregnant women after the launch of this program. Study design We conducted a multi-center survey in three Italian cities between March and June 2018. Collected data were analyzed anonymously, and included information about current recommendations of maternal immunization, antenatal care characteristics and reasons for accepting or rejecting vaccination. Results A total of 743 pregnant women completed the survey. Half of the study population were aged 25–35 years and 88 % were Italian. Only 18 % pregnant women received advice to be vaccinated. In this group, the vaccine was recommended in most cases by an obstetrician-gynecologist (68 %) and during a routine antenatal visit (74 %). Self-reported influenza and pertussis vaccination coverage was 6.5 % (95 % confidence interval, 4.9 %–8.5 %) and 4.8 % (95 % confidence interval, 3.5 %–6.6 %), respectively. The main vaccination barriers identified were lack of vaccine recommendation by any health-care provider (81 %) and safety concerns (18 %). Respondents mentioned the willingness to protect their offspring (82 %) and themselves (66 %) and having received immunization advice by a maternal care provider (62 %), as the main vaccination facilitators. Conclusions Lack of immunization advice by health-care providers and safety concerns were the main vaccination barriers against influenza and pertussis, among surveyed pregnant women. Vaccine delivery in the antenatal care setting could lead to increase of vaccine acceptance among pregnant women.